Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 17 1 2010 10.5194/npg-17-37-2010 http://www.nonlin-processes-geophys.net/17/37/2010/ http://www.nonlin-processes-geophys.net/17/37/2010/npg-17-37-2010.html http://www.nonlin-processes-geophys.net/17/37/2010/npg-17-37-2010.pdf 37 47 2010-01-22 Vertical mixing and coherent anticyclones in the ocean: the role of stratification I. Koszalka inga.koszalka@geo.uio.no L. Ceballos A. Bracco Institute of Geosciences, University of Oslo, 1022 Blinden, 0315 Oslo, Norway School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, GA 30332, USA The role played by wind-forced anticyclones in the vertical transport and mixing at the ocean mesoscale is investigated with a primitive-equation numerical model in an idealized configuration. The focus of this work is to determine how the stratification impacts such transport. <br><br> The flows, forced only at the surface by an idealized wind forcing, are predominantly horizontal and, on average, quasigeostrophic. Inside vortex cores and intense filaments, however, the dynamics is strongly ageostrophic. <br><br> Mesoscale anticyclones appear as "islands" of increased penetration of wind energy into the ocean interior and they represent the maxima of available potential energy. The amount of available potential energy is directly correlated with the degree of stratification. <br><br> The wind energy injected at the surface is transferred at depth through the generation and subsequent straining effect of Vortex Rossby Waves (VRWs), and through near-inertial internal oscillations trapped inside anticyclonic vortices. Both these mechanisms are affected by stratification. 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